Trouble Shooting - Kenwood NX-820H Service Manual

Fault Diagnosis of the BGA (Ball Grid Array) IC
Overview
A fl owchart for determining whether or not the transceiver can be powered on (the LCD does not function even if the power
switch is turned on) due to broken BGA parts.
BGA parts
ASIC (IC507), DSP (IC502), FLASH (IC501), SRAM (IC503)
When the BGA IC is problematic, please bring the printed circuit board (X57-8240-14 /-15 /-16 /-17) in for service. Various
ESN/default adjustment values are written on the printed circuit board for service.
Additionally various ESN stickers are included.
After the printed circuit board has been readjusted, please attach any ESN stickers to the chassis. When "ESN Validation" is
used with Trunking, you must modify the ESN register.
Checking power supply voltage
Checking voltage
Points to be checked
33M IC401 (5 pin)
15M IC408 (5 pin)
33A IC406 (5 pin)
Power supply of each device is connected through the coil.
[ASIC]
33M: L508, 15M: L510, 33A: R571
[DSP]
33M: L503, 15M: R505
[FLASH]
33M: L501
[SRAM]
33BU: L504
Checking the clock
Checking the clock
Points to be checked
18.432MHz IC506 (4 pin)
Checking the Reset/Control signal
Checking the control signal input to the ASIC
Points to be checked
RST (RESET) IC504 (1 pin)
/BINT IC402 (1 pin)
/OVRB D403 (Cathode side)
Checking the ASIC input switch signal
The POWER key is pressed and held.
Points to be checked
POWER R690
The ignition key is kept ON.
Points to be checked
/IGN C633 (Q504-Collector Side)
Checking the output signal
from the ASIC
Points to be checked
/FRST R516

TROUBLE SHOOTING

When an abnormal
value is confirmed.
Normal voltage
3.3V
1.5V
3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage (3.3V)
18.432MHz
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
3.3V
3.3V
When a normal
value is confirmed.
Confirmed voltage
ON: 0V
OFF: 3.3V
When an abnormal
Confirmed voltage
value is confirmed.
ON: 0V
OFF: 3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
When a normal
value is confirmed.
NX-820H(G)/820H
Checking for an abnormal point
33M has an abnormal voltage.
[ASIC]
Remove L508 to check the voltage of the 33M.
If the voltage becomes normal, the ASIC is broken.
[DSP]
Remove L503 to check the voltage of the 33M.
If the voltage becomes normal, the DSP is broken.
[FLASH]
Remove L501 to check the voltage of the 33M.
If the voltage becomes normal, the FLASH is broken.
[SRAM]
Remove L504 to check the voltage of the 33M.
If the voltage becomes normal, the SRAM is broken.
15M has an abnormal voltage.
[ASIC]
Remove L510 to check the voltage of the 15M.
If the voltage becomes normal, the ASIC is broken.
[DSP]
Remove R505 to check the voltage of the 15M.
If the voltage becomes normal, the DSP is broken.
33A has an abnormal voltage.
[ASIC]
Remove R571 to check the voltage of the 33A.
If the voltage becomes normal, the ASIC is broken.
If the voltage is not corrected, there is a problem
other than the BGA parts.
Remove the R556 . If it oscillates normally, the DSP
and ASIC may be broken.
Remove the R501. If it oscillates normally, the DSP
and ASIC may be broken.
The BGA parts are not broken.
Check the other point then BGA parts.
If the /FRST is always 0V, the ASIC is broken.
If the /FRST repeats 3.3V and 0V at intervals,
the ASIC, FLASH and SRAM may be broken.
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